水基钻井液防塌封堵材料封堵特性实验研究

Experimental study on plugging characteristics of plugging materials used in water-based drilling fluids

提高钻井液封堵能力是有效解决硬脆性页岩、煤层等复杂地层井壁失稳的主要技术手段。本文以在一定温度、压力条件下30 min的滤失量为评价标准,对几种封堵材料的封堵特性进行了实验研究。结果表明:除超细碳酸钙外,其他材料随着加量的增加,封堵效果越来越好;乳化沥青、乳化石蜡和油溶性酚醛树脂随着温度的升高,封堵效果变差,而聚乙二醇和聚酯先变差然后又有一定程度的恢复;聚酯和超细碳酸钙能够快速封堵微裂缝;几种封堵剂均对钻井液的流变性能有较明显的影响。对各封堵材料的封堵机理分析表明:不同的封堵材料具有不同的封堵特性,分别适应不同的温度、压力条件。只有根据井下实际情况,有针对性地选择与之相适应的封堵材料,才能有效提高水基钻井液的封堵能力。

Improving the sealing ability of drilling fluids is the primary technical way to effectively solve the borehole instability in hard and brittle shale and coal.With the filtration loss for 30 minutes under specific temperature and pressure as the evaluation standard,the plugging characteristics of several plugging materials are experimentally studied.The results showed that the sealing effect of the materials increased with the addition amount except for ultra-fine calcium carbonate.The plugging effect of emulsified asphalt,emulsified paraffin,and oil-soluble phenolic resin deteriorated with increase of temperature,while the plugging effect of polythene glycol and polyester first deteriorated and then had a certain degree of recovery.Polyester and ultra-fine calcium carbonate can quickly plug micro-cracks.These plugging materials had a significant impact on the rheological properties of drilling fluids.Analysis of the plugging mechanism of each plugging material shows that different plugging materials have different plugging characteristics and are suitable for different temperature and pressure conditions.The plugging capacity of the water-based drilling fluid can be effectively improved only if the plugging material is selected depending on specific downhole conditions.